/*eslint-disable*/
const l = 42, // 滑块边长
  r = 10, // 滑块半径
  w = 310, // canvas宽度
  h = 155, // canvas高度
  PI = Math.PI
const L = l + r * 2 // 滑块实际边长

function getRandomNumberByRange(start, end) {
  return Math.round(Math.random() * (end - start) + start)
}

function createCanvas(width, height) {
  const canvas = createElement('canvas')
  canvas.width = width
  canvas.height = height
  return canvas
}

function createImg(onload) {
  const img = createElement('img')
  img.crossOrigin = "Anonymous"
  img.onload = onload
  img.onerror = () => {
    img.src = getRandomImg()
  }
  img.src = getRandomImg()
  return img
}

function createElement(tagName) {
  return document.createElement(tagName)
}

function addClass(tag, className) {
  tag.classList.add(className)
}

function removeClass(tag, className) {
  tag.classList.remove(className)
}

function getRandomImg() {
  return 'https://picsum.photos/300/150/?image=' + getRandomNumberByRange(0, 100)
}

function draw(ctx, operation, x, y) {
  ctx.beginPath()
  ctx.moveTo(x, y)
  ctx.lineTo(x + l / 2, y)
  ctx.arc(x + l / 2, y - r + 2, r, 0, 2 * PI)
  ctx.lineTo(x + l / 2, y)
  ctx.lineTo(x + l, y)
  ctx.lineTo(x + l, y + l / 2)
  ctx.arc(x + l + r - 2, y + l / 2, r, 0, 2 * PI)
  ctx.lineTo(x + l, y + l / 2)
  ctx.lineTo(x + l, y + l)
  ctx.lineTo(x, y + l)
  ctx.lineTo(x, y)
  ctx.fillStyle = '#fff'
  ctx[operation]()
  ctx.beginPath()
  ctx.arc(x, y + l / 2, r, 1.5 * PI, 0.5 * PI)
  ctx.globalCompositeOperation = 'xor'
  ctx.fill()
}

function sum(x, y) {
  return x + y
}

function square(x) {
  return x * x
}

class Ligsaw {
  constructor(el, success, fail) {
    this.el = el
    this.success = success
    this.fail = fail
  }

  init() {
    this.initDOM()
    this.initImg()
    this.draw()
    this.bindEvents()
  }

  initDOM() {
    const canvas = createCanvas(w, h) // 画布
    const block = canvas.cloneNode(true) // 滑块
    const sliderContainer = createElement('div')
    const refreshIcon = createElement('div')
    const sliderMask = createElement('div')
    const slider = createElement('div')
    const sliderIcon = createElement('span')
    const text = createElement('span')

    block.className = 'block'
    sliderContainer.className = 'sliderContainer'
    refreshIcon.className = 'refreshIcon'
    sliderMask.className = 'sliderMask'
    slider.className = 'slider'
    sliderIcon.className = 'sliderIcon'
    text.innerHTML = '向右滑动滑块填充拼图'
    text.className = 'sliderText'

    const el = this.el
    el.appendChild(canvas)
    el.appendChild(refreshIcon)
    el.appendChild(block)
    slider.appendChild(sliderIcon)
    sliderMask.appendChild(slider)
    sliderContainer.appendChild(sliderMask)
    sliderContainer.appendChild(text)
    el.appendChild(sliderContainer)

    Object.assign(this, {
      canvas,
      block,
      sliderContainer,
      refreshIcon,
      slider,
      sliderMask,
      sliderIcon,
      text,
      canvasCtx: canvas.getContext('2d'),
      blockCtx: block.getContext('2d')
    })
  }

  initImg() {
    const img = createImg(() => {
      this.canvasCtx.drawImage(img, 0, 0, w, h)
      this.blockCtx.drawImage(img, 0, 0, w, h)
      const y = this.y - r * 2 + 2
      const ImageData = this.blockCtx.getImageData(this.x, y, L, L)
      this.block.width = L
      this.blockCtx.putImageData(ImageData, 0, y)
    })
    this.img = img
  }

  draw() {
    // 随机创建滑块的位置
    this.x = getRandomNumberByRange(L + 10, w - (L + 10))
    this.y = getRandomNumberByRange(10 + r * 2, h - (L + 10))
    draw(this.canvasCtx, 'fill', this.x, this.y)
    draw(this.blockCtx, 'clip', this.x, this.y)
  }

  clean() {
    this.canvasCtx.clearRect(0, 0, w, h)
    this.blockCtx.clearRect(0, 0, w, h)
    this.block.width = w
  }

  bindEvents() {
    this.el.onselectstart = () => false
    this.refreshIcon.onclick = () => {
      this.reset()
    }

    let originX, originY, trail = [], isMouseDown = false
    this.slider.addEventListener('mousedown', function (e) {
      originX = e.x, originY = e.y
      isMouseDown = true
    })
    document.addEventListener('mousemove', (e) => {
      if (!isMouseDown) return false
      const moveX = e.x - originX
      const moveY = e.y - originY
      if (moveX < 0 || moveX + 38 >= w) return false
      this.slider.style.left = moveX + 'px'
      var blockLeft = (w - 40 - 20) / (w - 40) * moveX
      this.block.style.left = blockLeft + 'px'

      addClass(this.sliderContainer, 'sliderContainer_active')
      this.sliderMask.style.width = moveX + 'px'
      trail.push(moveY)
    })
    document.addEventListener('mouseup', (e) => {
      if (!isMouseDown) return false
      isMouseDown = false
      if (e.x == originX) return false
      removeClass(this.sliderContainer, 'sliderContainer_active')
      this.trail = trail
      const {spliced, TuringTest} = this.verify()
      if (spliced) {
        if (TuringTest) {
          addClass(this.sliderContainer, 'sliderContainer_success')
          this.success && this.success()
        } else {
          addClass(this.sliderContainer, 'sliderContainer_fail')
          this.text.innerHTML = '再试一次'
          this.reset()
        }
      } else {
        addClass(this.sliderContainer, 'sliderContainer_fail')
        this.fail && this.fail()
        setTimeout(() => {
          this.reset()
        }, 1000)
      }
    })
  }

  verify() {
    const arr = this.trail // 拖动时y轴的移动距离
    const average = arr.reduce(sum) / arr.length // 平均值
    const deviations = arr.map(x => x - average) // 偏差数组
    const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length) // 标准差
    const left = parseInt(this.block.style.left)
    return {
      spliced: Math.abs(left - this.x) < 10,
      TuringTest: average !== stddev // 只是简单的验证拖动轨迹，相等时一般为0，表示可能非人为操作
    }
  }

  reset() {
    this.sliderContainer.className = 'sliderContainer'
    this.slider.style.left = 0
    this.block.style.left = 0
    this.sliderMask.style.width = 0
    this.clean()
    this.img.src = getRandomImg()
    this.draw()
  }
}

export default {
  init: function (element, success, fail) {
    new Ligsaw(element, success, fail).init()
  }
}
